My main pc (the one in my room) is unaccessible. One day i was just watching a film and i got a loads of windows opened, so my first reaction was to unplug my internet.

As soon as i did that i got thousands of errors saying 'Avira anti virus has encountered an error' I don't use avira and have never downloaded avira. They keep opening and opening. I then opened task manager and went into processes and it keeps opening Explorer.exe LOADS of times, like 209 times.

This makes my pc unaccessible in normal mode. I tried scanning in safe mode with avast! but nothing happened when the virus was found. cannot delete or move to chest.

The virus is called VBS:AGENT-CM[TRJ] If anyone could help i'd very much appreciate it.

Looks like you are in the stew pot!
About the only way to sanitize the drive is to wipe it, by deleting any partitions, shut down and start over. But you will loose all data.
You could slave the drive in another system that has a good anti-virus program, to clean it up. But you still may loose a lot of data. Virus strains love executable files.. and infest them!
McAfee has a "Stinger" program that works well on infected systems, and you may have some luck with it.. http://vil.nai.com/vil/stinger/

Be very wary of any pop-up ads that want you to try or DL programs. Even clicking on the "X" to close the window will bring the grunge into your system! Use the task bar tab for the window, close it from there. But there still are those programs that load into your system without your knowledge.. in the form of tattle cookies that bring in bits frequently, then when all the bits are in, the battle starts! Not all sites are safe. Use Firefox as your default browser, which blocks most pop-up windows by default.

That wouldn't have done a dang thing for this problem. He had scareware installed that needed to be removed. It'd do it on any browser you could think of, and if he did manage to block the popups, he'd have a nice trojan sitting there being ignored.